In the normal fermentation of brewer's wort in the production of beer and malt beverages, about 15% to 30% of the volume of the fermenting vessel is headspace used to accommodate the generation of foam caused by the initial uptake of carbohydrate consumption in the fermentation process. In the fermenting vessels having a high height-to-diameter ratio, the headspace will generally be about 20% to 30% of the volume of the vessel due to the increased tendency for foam generation in a taller vessel, while in vessels having a lower height-to-diameter ratio, the headspace will comprise about 15% to 20% of the volume of the vessel.
Lowering of the fermentation temperature will reduce the rate of foam generation, but will also prolong the duration of the fermentation which is undesirable from a production standpoint.
In normal brewing fermentation, the wort to be fermented has a solids content in the range of about 11.degree. to 18.degree. Plato, and when using a wort having a solids content in the upper portion of this range, the fermented substrate is diluted after fermentation to the desired and gravity, thereby increasing the production capacity of existing equipment. While it would be desirable to ferment a wort of higher solids content than 18.degree. Plato, and therefore increase the productivity without the use of additional capital equipment, attempts to ferment wort of a higher gravity, such as 18.degree. to 24.degree. Plato, have not been successful from a commercial standpoint, for they require extraordinarily long periods to achieve complete fermentation under normal fermentation conditions. In order to make the most effective use of capital equipment, prolonged fermentation periods are not desired.
It has also been found that complete fermentation of brewer's wort having an initial solids content of above 24.degree. Plato and in the range of 24.degree. to 36.degree. Plato, cannot be obtained by traditional practices, regardless of the time and temperature of fermentation, because activity of the yeast stopped long before limit attenuation was reached.